Method for recovering refrigerant from a refrigeration equipment

ABSTRACT

A method for recovering refrigerant from an external refrigeration equipment by a refrigerant recovery device includes recovering the refrigerant from the refrigeration equipment in a main recovering process. A small amount of heated refrigerant is recharged into the refrigeration equipment in a temporary refrigerant recharge process. An additional recovering process for emptying of a residual refrigerant from the refrigeration equipment is performed after finishing the temporary refrigerant recharge process.

This invention relates to a method for recovering refrigerant of anexternal refrigeration equipment.

STATE OF THE ART

U.S. Pat. No. 5,720,184 discloses a low pressure refrigerant recoveryrecycle machine. The machine comprises a compressor and a refrigerantpump. The refrigerant pump connected to the refrigeration unit torecover the refrigerant and the compressor compresses the refrigerantthat is recovered by the refrigerant pump.

ADVANTAGES OF THE INVENTION

The method of refrigerant recovery according to the independent claimshave the following advantages.

The method of recovering refrigerant from a refrigeration equipmentintroduces a small amount of the high temperature high pressurerefrigerant into the refrigeration equipment. This increases thetemperature and pressure inside the refrigeration equipment. This alsochanges the state of the refrigerant inside the refrigeration equipment.This allows the compressor to recover additional refrigerant from therefrigeration equipment. Thus lesser amount of refrigerant is releasedinto the atmosphere. This would reduce the pollutant released into theatmosphere, thereby reducing pollution considerably. This increases theworking efficiency of the refrigerant recovery device.

Further improvements and/or advantages are realised by the features ofthe dependent patent claims.

Due to increase in temperature and pressure inside the refrigerationequipment the pressure equalization while the refrigerant is recoveredwill be slower. Hence additional refrigerant can be recovered. Thisincreases the ability of the refrigerant recovery device to recoverrefrigerant.

The change in state of the refrigerant in the refrigeration equipmentenables easier recovery of the refrigerant. The compressor has to beswitched on for a shorter period for recovering the same amount ofrefrigerant. This reduces the power consumption. This in turn reducesthe operating cost of the using the refrigerant recovery device.

When residual refrigerant is recovered from the refrigeration equipment,the amount of refrigerant released into the atmosphere is reducedconsiderably. This helps to reduce pollution.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Different modes of the invention are disclosed in detail in thedescription and illustrated in the accompanying drawing:

FIG. 1 illustrates a refrigerant recovery comprising various componentsand connection between the various components.

FIG. 1 illustrates a refrigerant recovery device 10. The refrigerantrecovery device 10 is connected to an external refrigeration equipment12 through a valve block 14. The valve block 14 comprises valves, whichare adapted to establish a connection between the various components ofthe refrigerant recovery device 10 and refrigeration equipment 12. Thevalves in the valve block 14 are switched from a closed to an openposition so as to establish a connection between a compressor 16 and arefrigerant tank 18 of the refrigeration equipment 12. The refrigerantrecovery device 10 is used to recover refrigerant as well as to rechargerefrigerant into the refrigeration equipment 12. The recovery ofrefrigerant from the refrigeration equipment 12 and storing ofrefrigerant by the refrigerant recovery device 12 is done through arefrigerant recovery path 20. The recharging of refrigerant from therefrigerant recovery device 12 to refrigeration equipment is donethrough a refrigerant recharge path 22. In the refrigerant recharge path22 the refrigerant flows from the refrigerant tank 18 is heated by theheating element 24 and recharged to the refrigeration equipment 12.

Refrigeration equipments 12 are widely used in many applicationsincluding air conditioning systems, refrigerators and the like. Theserefrigeration equipments 12 use a refrigerant which provide cooling toan area or room in which they are fitted. The working principle of therefrigerant in the refrigeration equipment is that it absorbs heat whilepassing through various components of the refrigeration equipment. Thiscools the air around the refrigeration equipment and the cool air isthen blown to the area or room where the refrigeration equipment isinstalled.

Due to prolonged usage of the refrigerant in the refrigeration equipment12 the ability of the refrigerant to cool is reduced. Also there is apossibility that the refrigerant get contaminated with oil and moisture,which also reduces the ability of the refrigerant to cool the area orroom where the refrigeration equipments 12 are installed. Hence it isrequired that the refrigerant is removed from the refrigerationequipment 12 and is recharged with new refrigerant. For the purpose ofrecovering the refrigerant and recharging the refrigerant a refrigerantrecovery device 10 is used.

The refrigerant recovery device 10 is usually a stand alone device whichis connected to the refrigeration equipment 12 while the refrigerationequipment 12 is being serviced. The refrigerant recovery device 10comprises at least, a valve block 14, a compressor 16 and a refrigeranttank 18. The valve block 14 comprises valves, which are usually solenoidvalves. The valves of the valve block 14 can be switched from a closedposition to an open position, thereby establishing connection betweenthe various components of the refrigerant recovery device 10. The valvesin the valve block 14 can be switched from a closed position to an openposition to establish a connection between the refrigerant recoverydevice 10 and the refrigeration equipment 12. The compressor 16 is adevice which is capable of receiving fluid or gas at a particularpressure and increases the pressure of the fluid or gas that isreceived. A heating element 24 may be a electric heating coil woundaround the tube through which the refrigerant is recharged to therefrigeration equipment 12. The heating element 24 increases thetemperature of the refrigerant and the state of the refrigerant changesfrom liquid to gas. Due to the change of state of the refrigerant thepressure of the refrigerant that is recharged to the refrigerationequipment 12 also increases. The refrigerant tank 18 is a tank where therecovered refrigerant is store. The stored refrigerant is reused byrecharging the refrigerant to the refrigeration equipment 12.

While servicing refrigeration equipment 12 three particular tasks areinvolved viz (i) recovery of the refrigerant from the refrigerationequipment 12, (ii) evacuation of air and moisture from the refrigerationequipment 12 and (iii) refilling or recharging the refrigerationequipment 12 with clean refrigerant. The method used by a conventionalrefrigerant recovery device in the three tasks can be explained asfollows. The valve block 14 establishes a connection between therefrigerant recovery device 10 and the refrigeration equipment 12. Whenthe refrigerant recovery device 10 is switched on the compressor 16 isable to recover the refrigerant from the refrigeration device 12. Therecovered refrigerant is stored in the refrigerant tank 18. A vacuumpump 16 is used to evacuate the refrigeration device 10. Once therefrigeration equipment 12 is evacuated the air and moisture andremaining recovered refrigerant is released to the atmosphere. After theevacuation the refrigeration equipment 12 is recharged with refrigerantfrom the refrigerant tank 18. One disadvantage of this method ofrecovery and recharge is that the remaining refrigerant which is removedfrom the refrigeration equipment using the vacuum pump is released tothe atmosphere. The release of these refrigerants to the atmosphere isharmful. It is necessary that the amount of refrigerant released in theatmosphere should be minimized.

Also when the refrigeration equipment 12 is in use there is apossibility that some amount of refrigerant gets stuck at some cornersin the refrigeration equipment. When the refrigerant is being recoveredthis residual refrigerant which is stuck in the refrigeration equipmentcannot be removed. Hence the amount of refrigerant that has to berecharged to the refrigeration equipment will be miscalculated. Thusextra refrigerant will have to be recharged which increases the cost forrecharging refrigerant.

In accordance with this invention the refrigerant recovery device 10 isable to recover additional residual refrigerant which may be stuck inthe refrigeration equipment 12. This reduces the amount of refrigerantthat is released to the atmosphere. The method of recovering refrigerantin accordance with this invention can be explained as follows.

A connection is established between the refrigerant recovery device 10and the refrigeration equipment 12 through the valve block 14 forperforming a main recovering process. At least one valve in the valveblock is switched to an open position for this purpose. Once theconnection is established recovery of the refrigerant from therefrigeration equipment is initiated through the refrigerant recoverypath 20 by switching on the compressor. In the refrigerant recovery path20 the refrigerant flows from the refrigeration equipment 12 through thevalve block 14 to the compressor 16 and is stored in the refrigeranttank 18. When the compressor 16 is switched on the pressure in the inletpath of the compressor 16 is lower that the pressure in therefrigeration equipment 12. The refrigerant flows from the high pressurerefrigeration equipment 12 to the low pressure inlet path of thecompressor. The compressor 16 increases the pressure of the refrigerantand is stored in the refrigerant tank 18. Once the refrigerant isrecovered from the refrigeration equipment 12 to the refrigerant tankthe valve in the valve block 14 is switched to closed position.

After recovering the refrigerant from the refrigeration equipment 12 bythe main recovering process described above, a temporary refrigerantrecharge process takes place in which a small amount of heatedrefrigerant from the refrigerant tank 18 is recharged into therefrigeration equipment 12. For this purpose a connection is establishedbetween the refrigerant tank 18 and the refrigeration equipment 12through the refrigerant recharge path 22. In the refrigerant rechargepath 22 the refrigerant flows from the refrigerant tank 18 through theheating element 24, valve block 14 to the refrigeration equipment 12.The small amount of heated refrigerant at the temporary refrigerantrecharge process represents less than 20% of the whole capacity of therefrigerant inside of the refrigeration equipment 12, especially lessthan 10% of the whole capacity of the refrigerant inside of therefrigeration equipment 12. The small amount of heated refrigerant isintroduced into the refrigeration equipment 12 in more than one pulse,for example in three pulses.

When the refrigerant passes along the heating element 24, there is asudden increase in the temperature and pressure of the refrigerant. Herethe temperature and pressure of the refrigerant is higher thantemperature and pressure of the refrigerant during a conventionalrecharge operation. The increased pressure and temperature of therecharged refrigerant ensures that the refrigerant is quickly rechargedto the refrigeration equipment. Further due the high temperature andpressure the state of the refrigerant recharged into the refrigerationequipment changes from liquid to gaseous.

When the refrigerant enters the refrigeration equipment 12 it changesthe state of the residual refrigerant that is present in therefrigeration equipment to gaseous state. This happens due to theincrease in temperature and consequent increase in pressure of therefrigerant inside the refrigeration equipment 12. Due to change instate of the residual refrigerant the high temperature and high pressurerefrigerant from the refrigeration equipment can be easily recoveredfrom the refrigeration equipment 12. Introducing high pressure and hightemperature refrigerant into the refrigeration equipment 12 increasesthe pressure and temperature inside the refrigeration equipment 12. Thismakes recovery of refrigerant from the refrigeration equipment 12easier.

After the temporary refrigerant recharge process is finished anadditional recovering process is performing for additionally emptying ofa residual refrigerant from the refrigeration equipment (12). Forrecovering the residual refrigerant in the additional recovering processat least one valve in the valve block is switched to an open positionfor this purpose. Once the connection is established recovery of therefrigerant from the refrigeration equipment is initiated through therefrigerant recovery path 20 by switching on the compressor. When thecompressor is switched on the pressure in the inlet path of thecompressor is lower than the pressure in the refrigeration equipment 12.The refrigerant flows from the high pressure refrigeration equipment tothe low pressure inlet path of the compressor. The compressor increasesthe pressure of the refrigerant and is stored in the refrigerant tank18. Once the refrigerant is recovered from the refrigeration equipment12 to the recovery tank the valve in the valve block 14 is switched toclosed position.

An advantage of introducing refrigerant that is heated using the heatingelement is that it increases the temperature of the refrigerant beingrecharged into the refrigeration equipment 12 consequently pressure alsoincreases. This leads to change in state of the refrigerant in therefrigeration equipment 12 from liquid state to gaseous state. It iseasier to recover refrigerant which is in gaseous state. As pressure andtemperature inside the refrigeration equipment 12 is higher than usual.Hence, the compressor 12 can easily and quickly recover refrigerant. Thecompressor 16 will have to be switched on for a shorter period of timeto recover additional refrigerant from the refrigeration equipment 12.Also due to high temperature and pressure the liquid refrigerant thatmay be stuck in various parts of the refrigeration equipment isconverted to gaseous state and are easily recovered. This method ofrecovering additional refrigerant ensures more than 95% refrigerant ofthe refrigerant from the refrigeration equipment 12. Another advantageof this method is that since additional refrigerant is recovered duringthe recovery process the total amount of refrigerant released into theatmosphere is reduced.

1. A method for recovering refrigerant from an external refrigerationequipment by a refrigerant recovery device, with the refrigerant of theexternal refrigeration equipment flowing from the refrigerationequipment through a refrigerant recovery path to a refrigerant tank ofthe recovery device, comprising: recovering the refrigerant from therefrigeration equipment in a main recovering process; recharging a smallamount of heated refrigerant into the refrigeration equipment in atemporary refrigerant recharge process; and performing an additionalrecovering process for emptying of a residual refrigerant from therefrigeration equipment after finishing the temporary refrigerantrecharge process.
 2. The method as claimed in claim 1, wherein, toperform the temporary refrigerant recharge process, the refrigerantrecovery path is closed and a recharge path which connects the tank withthe refrigeration equipment is opened.
 3. The method as claimed in claim2, further comprising: establishing a connection between the refrigerantrecovery device and the refrigeration equipment by switching on at leastone valve in a valve block; creating a low pressure at the inlet path ofa compressor by switching on said compressor; recovering the refrigerantfrom said refrigeration equipment to a refrigerant tank through therefrigerant recovery path comprising at least said valve block, saidcompressor and said refrigerant tank by the main recovering process;switching off said compressor; recharging the refrigerant from saidrefrigerant tank to said refrigeration equipment by keeping a heatingelement switched on through the refrigerant recharge path comprising atleast said valve block and said refrigerant tank by the refrigerantrecharge process; switching off said heating element; creating a lowpressure at the inlet path of said compressor by switching on saidcompressor; and emptying the rest of the refrigerant from saidrefrigeration equipment through said refrigerant recovery path by theadditional recovering process.
 4. The method as claimed in claim 1,wherein the increase in temperature of the refrigerant by the temporaryrefrigerant recharge process causes change of state of the refrigerantrecharged to said refrigeration equipment from liquid to gaseous.
 5. Themethod as claimed in claim 4, wherein the change in state of therefrigerant causes increase in pressure of the refrigerant recharged tosaid refrigeration equipment.
 6. The method as claimed in claim 1,wherein said temporary refrigerant recharge process increases thetemperature inside the refrigeration equipment.
 7. The method as claimedin claim 1, wherein said temporary refrigerant recharge process changesthe state of the refrigerant inside the refrigeration equipment.
 8. Themethod as claimed in claim 7, wherein said change in state of therefrigerant causes increase in pressure of the refrigerant in saidrefrigeration equipment.
 9. The method as claimed in claim 7, whereinperforming said temporary refrigerant recharge process to saidrefrigeration equipment recovers additional refrigerant that is stuck indifferent parts of the refrigeration equipment.
 10. The method asclaimed in claim 1, wherein the small amount of heated refrigerant isintroduced into the refrigeration equipment in more than one pulse.